Not applicable.
Not applicable.
Not applicable.
This invention is directed to underarm compositions, in particular to antiperspirants containing a mixture of an xcex1,xcfx89-diene crosslinked silicone elastomer and a silicone rubber powder.
Silicone rubber powders having an average particle diameter of 0.1-200 micron (xcexcm) are disclosed in U.S. Pat. No. 5,628,989 (May 13, 1997), including their use in antiperspirants. Aqueous suspensions containing silicone rubber powders having an average particle diameter of 0.1-500 micron (xcexcm) are disclosed in U.S. Pat. No. 5,928,660 (Jul. 27, 1999), including their use in antiperspirants. An antiperspirant powder consisting of an antiperspirant salt and a silicone rubber powder having an average particle diameter of 0.1-200 micron (xcexcm) is disclosed in U.S. Pat. No. 6,126,927 (Oct. 3, 2000).
U.S. Pat. No. 5,654,362 (Aug. 5, 1997), while generally relating to xcex1,xcfx89-diene crosslinked silicone elastomers, suggests that xcex1,xcfx89-diene crosslinked silicone elastomers can be used as carriers for crosslinked silicone rubber particles, i.e., silicone rubber powders. While the ""362 patent in Example III teaches using xcex1,xcfx89-diene crosslinked silicone elastomers in antiperspirants, it fails to teach how to prepare an antiperspirant containing both xcex1,xcfx89-diene crosslinked silicone elastomers and silicone rubber powders.
According to the present invention, and quite unexpectedly, it was discovered that new and improved results can be obtained when antiperspirants contain a ratio of 1:2 to 1:6 of the silicone rubber powder to the xcex1,xcfx89-diene crosslinked silicone elastomer, i.e., one part silicone rubber powder to 2-6 parts of xcex1,xcfx89-diene crosslinked silicone elastomer. When the ratio is less than 1:2, an oil layer is formed in roll-on applications. When the ratio is above 1:6, the viscosity of the roll-on becomes too high for practical application.
This invention relates to an underarm composition containing as its basic components, (i) an antiperspirant or deodorant active ingredient, (ii) a vehicle, (iii) an emollient, and (iv) a blend of a silicone rubber powder and an xcex1,xcfx89-diene crosslinked silicone elastomer. The silicone rubber powder and the xcex1,xcfx89-diene crosslinked silicone elastomer are present in the blend in a weight ratio of 1:2 to 1:6, respectively.
Preferably, the underarm composition is anhydrous, and it may contain as an additional component (v) a wax.
These and other features of the invention will become apparent from a consideration of the detailed description.
Not applicable.
As used herein, the term silicone rubber powder is intended to mean compositions prepared generally according to methods described in U.S. Pat. No. 4,742,142 (May 3, 1988).
Silicone rubber powders, sometimes referred to as E-Powders, are spherical particles of vulcanized silicone rubber, i.e., crosslinked polydimethylsiloxanes (PDMS), having a mean particle size distribution on the order of 0.1-200 xcexcm. An aqueous emulsion process is used to prepare the silicone rubber powder as this process leads to a spherical shape for the particles, and it provides the desirable particle size distribution. In essence, the emulsion process consists of emulsifying a curable, liquid silicone elastomeric composition in water with one or more surface active agents followed by a curing step and finally removal of water. Inherent to the emulsion process are the spherical shape of the particles and a relatively good control of particle size distribution within a certain region.
Two curing reactions for crosslinking siloxane polymers are generally utilized, one being addition of a silicon hydride (xe2x89xa1SiH) to a vinyl functional siloxane in the presence of a platinum catalyst, i.e., hydrosilylation, and the other condensation of silanol functional siloxanes with reactive silicon. Polymers used to make silicone rubber powder are either OH or vinyl functional polymers, depending upon whether condensation or hydrosilylation is used for the crosslinking step. These polymers are usually of moderately low molecular weight (MW), such that their concomitant low viscosity make them easy to emulsify by conventional techniques. Polymers having viscosities under about 1000 cP (centipoise) are preferred for preparing silicone rubber powder.
Crosslinking agents can be practically any multifunctional reactive siloxane or silane that is soluble in the polymer. Silicon hydride (xe2x89xa1SiH) functional siloxanes are the crosslinkers of choice due to their high reactivity and the absence of byproducts. These can be either linear polymethylhydrogen siloxane or copolymers of polydimethylsiloxane polymethylhydrogen siloxane. The hydrosilylation reaction involving addition of xe2x89xa1SiH to a vinyl functional siloxane has the advantage that no byproducts are formed. In contrast, copious amounts of H2 are liberated from the condensation route involving reaction of xe2x89xa1SiH with xe2x89xa1SiOH.
The emulsification procedure is carried out using standard emulsion high shear equipment such as homogenizers or colloid mills. Surface active agents used can be either ionic or nonionic, or a combination of both, but nonionic is preferred. Preferred nonionic surfactants are alkyl ethoxylates. Levels of surfactant is on order of 0.5-5 percent by weight of the silicone polymer. It should be understood that the surface active agents remain with the silicone rubber powder upon removal of water.
Crosslinking in silicone rubber powders must occur after the particles have been formed. However, crosslinking will commence upon combining the three basic ingredients, (i) the functional polymer, (ii) the crosslinking agent, and (iii) the catalyst. Thus, some means must be used to ensure particle formation is complete prior to the onset of significant crosslinking. This can be accomplished by using catalyst inhibitors or by adding the catalyst after emulsification. In some cases, the emulsion is heated to increase the rate of crosslinking reactions. Once crosslinking is complete, the particles are harvested by removing water. Water removal can be accomplished by using processes like vacuum distillation or spray drying. In vacuum distillation, a mixer is used to provide heat and agitation under vacuum. Spray drying is the preferred method, however, as it is highly efficient and can be operated continuously.
As used herein, the term xcex1,xcfx89-diene crosslinked silicone elastomer is intended to mean xcex1,xcfx89-diene crosslinked silicone elastomers having no oxyalkylene units in their structure. They have been referred to generally in the art as non-emulsifying silicone elastomers, meaning that polyoxyalkylene units are absent. Otherwise, the xcex1,xcfx89-diene crosslinked silicone elastomers suitable for use according to this invention are the compositions described in U.S. Pat. No. 5,654,362.
As described in detail in the ""362 patent, the xcex1,xcfx89-diene crosslinked silicone elastomers are prepared by reacting (A) an xe2x89xa1Sixe2x80x94H containing polysiloxane of the formula R3SiO(Rxe2x80x22SiO)a(Rxe2x80x3HSiO)bSiR3 and optionally an xe2x89xa1Sixe2x80x94H containing polysiloxane of formula HR2SiO(Rxe2x80x22SiO)cSiR2H or formula HR2SiO(Rxe2x80x22SiO)a(Rxe2x80x3HSiO)bSiR2H where R, Rxe2x80x2, and Rxe2x80x3 are alkyl groups with 1-6 carbon atoms; a is 0-250; b is 1-250; and c is 0-250; with (B) an alpha,omega-diene of formula CH2xe2x95x90CH(CH2)xCHxe2x95x90CH2 where x is 1-20. The reaction is conducted in the presence of a platinum catalyst and in the presence of (C) a low molecular weight silicone oil or other solvent. The reaction system is non-aqueous in contrast to the reaction system used to prepare the silicone rubber powder.
For most practical purposes, the low molecular weight silicone oil or other solvent is generally a cyclic alkyl siloxane of the formula (Rxe2x80x2xe2x80x32SiO)d or linear alkyl siloxane of the formula Rxe2x80x2xe2x80x33SiO(Rxe2x80x2xe2x80x32SiO)eSiRxe2x80x2xe2x80x33 in which Rxe2x80x3 is an alkyl group containing 1-6 carbon atoms, d is 3-6 and e is 0-5. Most preferred, however, are volatile cyclic methyl siloxanes of the formula {(CH3)2SiO}d and volatile linear methyl siloxanes of the formula (CH3)3SiO{(CH3)2SiO}eSi(CH3)3 and in which d is 3-6 and e is 0-5, respectively. Preferably, the volatile methyl siloxane has a boiling point less than 250xc2x0 C. and a viscosity of 0.65-5.0 centistoke (mm2/s).
Some representative linear volatile methyl siloxanes are hexamethyldisiloxane (MM) with a boiling point of 100xc2x0 C., viscosity of 0.65 mm2/s, and formula Me3SiOSiMe3; octamethyltrisiloxane (MDM) with a boiling point of 152xc2x0 C., viscosity of 1.04 mm2/s, and formula Me3SiOMe2SiOSiMe3; decamethyltetrasiloxane (MD2M) with a boiling point of 194xc2x0 C., viscosity of 1.53 mm2/s, and formula Me3SiO(Me2SiO)2SiMe3; dodecamethylpentasiloxane (MD3M) with a boiling point of 229xc2x0 C., viscosity of 2.06 mm2/s, and formula Me3SiO(Me2SiO)3SiMe3; tetradecamethylhexasiloxane (MD4M) with a boiling point of 245xc2x0 C., viscosity of 2.63 mm2/s, and formula Me3SiO(Me2SiO)4SiMe3; and hexadecamethylheptasiloxane (MD5M) with a boiling point of 270xc2x0 C., viscosity of 3.24 mm2/s, and formula Me3SiO(Me2SiO)5SiMe3. Me in these and the following formulas represents the methyl group CH3.
Some representative cyclic volatile methyl siloxanes are hexamethylcyclotrisiloxane (D3), a solid at room temperature, with a boiling point of 134xc2x0 C. and formula (Me2SiO)3; octamethylcyclotetrasiloxane (D4) with a boiling point of 176xc2x0 C., viscosity of 2.3 mm2/s, and formula (Me2SiO)4; decamethylcyclopentasiloxane (D5) with a boiling point of 210xc2x0 C., viscosity of 3.87 mm2/s, and formula (Me2SiO)5; and dodecamethylcyclohexasiloxane (D6) with a boiling point of 245xc2x0 C., viscosity of 6.62 mm2/s, and formula (Me2SiO)6.
An extensive list of other types of appropriate low molecular weight silicone oils and solvents which can be used is also found in the ""362 patent. The xcex1,xcfx89-diene crosslinked silicone elastomer composition will generally comprise 2-20 percent by weight of the elastomer per se, and 80-98 percent by weight of the low molecular weight silicone oil or solvent.
Underarm compositions according to the invention will generally comprise about 15-35 percent by weight of the mixture of the silicone rubber powder and the xcex1,xcfx89-diene crosslinked silicone elastomer in a ratio of 1:2 to 1:6 of the silicone rubber powder to the xcex1,xcfx89-diene crosslinked silicone elastomer; an antiperspirant or deodorant active; an emollient; and a vehicle, i.e., a solvent. Other optional ingredients can be added to the underarm composition to enhance its properties or benefits, such as waxes, fillers, fragrances, dyes, pigments, anti-inflammatory agents, moisturizers, antioxidants, stabilizers, and preservatives.
In antiperspirant applications, an astringent is necessary to suppress perspiration. For an astringent, any well-known compound can be used. Some suitable examples include aluminum chloride, aluminum chlorohydrate, aluminum bromide, aluminum bromohydrate, aluminum zirconium trichlorohydrate glycine complexes, aluminum zirconium tetrachlorohydrate glycine complexes, and mixtures of aluminum chloride with aluminum chlorohydrate. The astringent is generally present in the composition in an amount of 20-25 percent by weight.
In deodorant applications, an antimicrobial or microbiocidal agent is necessary for suppressing the growth of microorganisms such as normal skin flora, which degrade sweat and cause body odor. Any well-known antimicrobial or microbiocidal agent can be used, among which are quaternary ammonium salts, alkyldiaminoethyl glycine chloride solutions, isopropylmethylphenol, and Triclosan, i.e., trichlorohydroxy diphenyl ether. The antimicrobial or microbiocidal agent is generally present in the composition in an amount of 0.01-10 percent by weight.
Generally, underarm compositions contain an emollient that is a liquid at room temperature for providing good adhesion and to maintain the compositions in a cream or liquid form. Some suitable examples include liquid paraffin; esters such hexyl laurate, isopropyl myristate, myristyl myristate, cetyl myristate, 2-octyldodecyl myristate, isopropyl palmitate, 2-ethylhexyl palmitate, butyl stearate, decyl oleate, 2-octyldodecyl oleate, myristyl lactate, cetyl lactate, lanolin acetate; fatty oils such as stearyl alcohol, cetostearyl alcohol, and oleyl alcohol; organic oils such as avocado oil, almond oil, olive oil, cacao oil, jojoba oil, sesame oil, safflower oil, soybean oil, camellia oil, squalane, castor oil, mink oil, cottonseed oil, coconut oil, beef fat, and pork fat; glycol ester oils such as polypropylene glycol monooleate or neopentyl glycol 2-ethylhexanoate; polyoxyalkylene ether oils such as polyoxyethylene lauryl ether or polyoxypropylene cetyl ether; alcohols such as ethanol, octyl dodecanol, cetyl alcohol or oleyl alcohol; and silicone oils such as dimethylsiloxanes, polymethylphenylsiloxanes, polymethylhydrogen siloxanes, dimethylsiloxane methylstearoxysiloxane copolymers, dimethylsiloxane methylcetyloxysiloxane copolymers, dimethylsiloxane methyl(polyoxyethyl)siloxane copolymers, dimethylsiloxane methyl(polyoxyethylene polyoxypropylene)siloxane copolymers, dimethylsiloxane methyl(polyoxypropylene)siloxane copolymers, cyclic polydimethylsiloxanes, cyclic polymethylphenylsiloxanes, cyclic polymethylhydrogen siloxanes, amino-modified polysiloxanes, epoxy-modified polysiloxanes, polyoxyalkylene-modified polysiloxanes, alkoxy-modified polysiloxanes, and alkyl-modified polysiloxanes. The emollient is generally present in the composition in an amount of 1-6 percent by weight.
The remainder of the underarm composition to 100 percent by weight will generally comprise a vehicle, and one or more optional ingredients typically included in underarm compositions. The vehicle can comprise any one or more of the low molecular weight silicone oils and/or solvents mentioned above.
When a wax is included as an optional ingredient, it will generally comprise a wax with a melting point of 50-110xc2x0 C. to provide good adhesion and to maintain the compositions in a semi-solid or solid state. Some suitable examples include organic waxes such as beeswax, carnauba wax, candelilla wax, ozocerite, ceresin, rice wax, vegetable wax, montan wax, paraffin, microcrystalline wax, stearyl alcohol, hydrogenated castor oil, lanolin, Vaseline, and cholesteryl stearate. Semi-solid or solid silicones can also be used such as alkoxy modified polysiloxanes, polyoxyalkylene modified polysiloxanes, and alkylmethyl modified polysiloxanes containing higher alkyl groups of 18-45 carbon atoms.
When a filler is used as an optional ingredient to improve adhesion to the skin, it will generally comprise a filler such as talc, mica, colloidal silica, kaolin, zinc oxide, magnesium carbonate, calcium carbonate, bentonite, hectorite, colloidal aluminum magnesium silicate, silk powder, polyethylene resin powder, TEFLON(copyright) powder, acrylic resin powder, polypropylene resin powder, polystyrene resin powder, vinyl chloride resin powder, cellulose powder, nylon resin powder, and polyorganosilsesquioxane powder.
If desired, purified water can be blended into the underarm compositions to provide emulsions. The underarm compositions can be emulsified with surfactants such as sorbitan aliphatic esters, polyoxyethylene sorbitol lanolin derivatives, polyoxyethylene aliphatic ethers, polyoxyethylene propylene glycol stearate, polyoxyethylene stearate, polyoxyethylene sorbitan aliphatic ethers, and polyoxypropylene-polyoxyethylene condensates.
The underarm compositions can be prepared in the form of a solid, semisolid, cream, liquid, or powder; and depending on its particular formulation, it can be applied to the skin by spraying, as a stick, or in a roll-on form. When a stick form is desired, it is prepared by heating the liquid oil ingredients, waxes, the mixture of the xcex1,xcfx89-diene crosslinked silicone elastomer and silicone rubber powder, astringents, antimicrobial or microbiocidal agents, and other optional ingredients, above the melting point of the waxes; stirring to homogeneity; and cooling to room temperature in a stick mold. The underarm compositions can be prepared by in a batch or continuous mode, using common devices such as homomixers, paddle mixers, colloid mills, propeller stirrers, homogenizers, in line continuous emulsifiers, ultrasonic emulsifiers, and vacuum kneaders.